Solid state sandwich concept: Designs, considerations and issues

Progress in analysis and design of solid state approaches to the solar power satellite microwave power transmission system is reviewed with special emphasis on the Sandwich concept and the issues of maintenance of low junction temperatures for amplifiers to assure acceptable lifetime. Ten specific issues or considerations are discussed and their resolution or status is presented

Initial MPTS study results: Design considerations and issues

One of the key issues identified during investigations of microwave power transmission systems from 1965 to 1976 was the need to assure that the billions of diodes on ground-based rectennas are sufficiently reliable to support long life times of approximately 30 years. Major systems studies conducted focused on waveguides; radio frequency interference and biological considerations; the relationship between performance, weight, and cost; risk assessment; crossed field directional amplifier noise; a 48 kW klystron; effects of the environment on propagation and phase control; rectenna technology; a rationale for the ground power density region; alternate technologies for orbital assembly; ionospheric effects and phase control; and reception conversion (rf to dc collector/converter)

Solid state SPS microwave generation and transmission study. Volume 1: Phase 2

The solid state sandwich concept for Solar Power Station (SPS) was investigated. The design effort concentrated on the spacetenna, but did include some system analysis for parametric comparison reasons. The study specifically included definition and math modeling of basic solid state microwave devices, an initial conceptual subsystems and system design, sidelobe control and system selection, an assessment of selected system concept and parametric solid state microwave power transmission system data relevant to the SPS concept. Although device efficiency was not a goal, the sensitivities to design of this efficiency were parametrically treated. Sidelobe control consisted of various single step tapers, multistep tapers, and Gaussian tapers. A preliminary assessment of a hybrid concept using tubes and solid state is also included. There is a considerable amount of thermal analysis provided with emphasis on sensitivities to waste heat radiator form factor, emissivity, absorptivity, amplifier efficiency, material and junction temperature

Feasibility Study of a Satellite Solar Power Station

A feasibility study of a satellite solar power station (SSPS) was conducted to: (1) explore how an SSPS could be flown and controlled in orbit; (2) determine the techniques needed to avoid radio frequency interference (RFI); and (3) determine the key environmental, technological, and economic issues involved. Structural and dynamic analyses of the SSPS structure were performed, and deflections and internal member loads were determined. Desirable material characteristics were assessed and technology developments identified. Flight control performance of the SSPS baseline design was evaluated and parametric sizing studies were performed. The study of RFI avoidance techniques covered (1) optimization of the microwave transmission system; (2) device design and expected RFI; and (3) SSPS RFI effects. The identification of key issues involved (1) microwave generation, transmissions, and rectification and solar energy conversion; (2) environmental-ecological impact and biological effects; and (3) economic issues, i.e., costs and benefits associated with the SSPS. The feasibility of the SSPS based on the parameters of the study was established

Exposure to males, but not receipt of sex peptide, accelerates functional aging in female fruit flies

1. Increased exposure to males can affect females negatively, reducing female life span and fitness. These costs could derive from increased mating rate and also harassment by males. Additionally, early investment in reproduction can increase the onset or rate of senescence in reproductive traits. Hence, there is a tight link between reproduction and ageing. 2. Here, we assess how mating and encounter rate with males impacts declines in female functional traits that are not directly involved in reproduction. In Drosophila melanogaster fruit flies, exposure to males and mating reduces female life span through harassment and receipt of seminal proteins, including sex peptide (SP). We manipulated the intensity of female exposure to males and regularly assessed female stress responses and recorded physiological traits over her lifetime. 3. Both mating itself and increased exposure to males accelerate declines in female climbing ability and starvation resistance. However, this is not related to changes in female body mass or fat storage. Moreover, these declines are not driven by the receipt of SP. 4. Our results suggest some synchrony in senescence across traits in response to female exposure to males; however, this is not universal, as we did not find this for physiological traits. Synchrony in senescence has been theorized but little supported in the literature. It is clear that ageing is a multifaceted trait; to understand environmental impacts on ageing rates, we must measure more than life span and indeed measure senescence in multiple traits. Specifically, our work shows that we must identify which female traits are sensitive to elevated mating activity to understand the impact of antagonistic interactions between the sexes on female ageing patterns

Microwave power transmission system studies. Volume 2: Introduction, organization, environmental and spaceborne systems analyses

Introduction, organization, analyses, conclusions, and recommendations for each of the spaceborne subsystems are presented. Environmental effects - propagation analyses are presented with appendices covering radio wave diffraction by random ionospheric irregularities, self-focusing plasma instabilities and ohmic heating of the D-region. Analyses of dc to rf conversion subsystems and system considerations for both the amplitron and the klystron are included with appendices for the klystron covering cavity circuit calculations, output power of the solenoid-focused klystron, thermal control system, and confined flow focusing of a relativistic beam. The photovoltaic power source characteristics are discussed as they apply to interfacing with the power distribution flow paths, magnetic field interaction, dc to rf converter protection, power distribution including estimates for the power budget, weights, and costs. Analyses for the transmitting antenna consider the aperture illumination and size, with associated efficiencies and ground power distributions. Analyses of subarray types and dimensions, attitude error, flatness, phase error, subarray layout, frequency tolerance, attenuation, waveguide dimensional tolerances, mechanical including thermal considerations are included. Implications associated with transportation, assembly and packaging, attitude control and alignment are discussed. The phase front control subsystem, including both ground based pilot signal driven adaptive and ground command approaches with their associated phase errors, are analyzed

Microwave Power Transmission System Studies. Volume 1: Executive Summary

A study of microwave power generation, transmission, reception and control was conducted as a part of a program to demonstrate the feasibility of power transmission from geosynchronous orbit. A summary is presented of results concerning design approaches, estimated costs (ROM), critical technology, associated ground and orbital test programs with emphasis on dc to rf conversion, transmitting antenna, phase control, mechanical systems, flight operations, ground power receiving-rectifying antenna with systems analysis, and evaluation. Recommendations for early further in-depth studies complementing the technology program are included

Building Cooperative Networks

We study the cooperation problem in the framework of evolutionary game theory using the prisoner's dilemma as metaphor of the problem. Considering the growing process of the system and individuals with imitation capacity, we show conditions that allow to form highly cooperative networks of any size and topology. Introducing general considerations of real systems, we reduce the required conditions for cooperation to evolve approaching the benefit-cost ratio r to the theoretical minimum r=1, when the mean connectivity of the individuals is increased. Through the paper, we distinguish different mechanisms that allow the system to maintain high levels of cooperation when the system grows by incorporation of defectors. These mechanisms require heterogeneity among individuals for cooperation to evolve. However, the required conditions and heterogeneities are drastically reduced as compared to those required for static networks.Comment: 24 pages, 8 figure

A qualitative study of e-cigarette emergence and the potential for renormalisation of smoking in UK youth

Background: Growth of e-cigarette use among smokers has raised concerns over uptake by non-smokers, particularly young people. Legislative changes aimed in part at reducing youth exposure to e-cigarettes include the EU Tobacco Products Directive (TPD). A core justification for such measures is the belief that e-cigarettes can lead to tobacco smoking through mechanisms of renormalisation including: mimicking and normalizing the act of smoking; increasing product acceptability via marketing; nicotine exposure. These mechanisms are here explored in relation to findings from qualitative research. Methods: This paper reports results from twenty-one group interviews with 14–15 year olds in Wales, England and Scotland, conducted as part of an ongoing evaluation of the impact of the TPD on youth smoking and e-cigarette use. Interviews were conducted around the end of the transitional period for TPD implementation, and explored perceptions of e-cigarettes and tobacco, as well as similarities and differences between them. Results: Young people differentiated between tobacco and e-cigarettes, rejecting the term e-cigarette in favour of alternatives such as ‘vapes’. Experimental or occasional use was common and generally approved of where occurring within social activity with peers. However, regular use outside of this context was widely disapproved of, unless for the purpose of stopping smoking. Increased prevalence of e-cigarettes did not challenge strongly negative views of smoking or reduce perceived harms caused by it, with disapproval of smoking remaining high. Nicotine use was variable, with flavour a stronger driver for choice of e-liquid, and interest more generally. Conclusion: The extent to which participants differentiated between vaping and smoking, including styles and reasons for use in adults and young people; absence of marketing awareness; and continued strong disapproval of smoking provides limited support for some of the potential mechanisms through which e-cigarettes may renormalise smoking. However caution over nicotine exposure is still necessary

Error Thresholds on Dynamic Fittness-Landscapes

In this paper we investigate error-thresholds on dynamics fitness-landscapes. We show that there exists both lower and an upper threshold, representing limits to the copying fidelity of simple replicators. The lower bound can be expressed as a correction term to the error-threshold present on a static landscape. The upper error-threshold is a new limit that only exists on dynamic fitness-landscapes. We also show that for long genomes on highly dynamic fitness-landscapes there exists a lower bound on the selection pressure needed to enable effective selection of genomes with superior fitness independent of mutation rates, i.e., there are distinct limits to the evolutionary parameters in dynamic environments.Comment: 5 page